This invention relates to a fine pattern inspection device for inspecting a fine pattern comprising a plurality of pattern elements which have the same form. Such a fine pattern inspection device is particularly useful in inspection for a wafer of a semiconductor memory device such as a DRAM (Dynamic Random Access Memory) in which a plurality of memory cells are formed in array and for a mask which is used for fabricating the semiconductor memory device.
An example of the fine pattern inspection device is disclosed in Japanese Unexamined Patent Publication No. 200415/1986 (Tokkai sho 61-200415). The pattern inspection device comprises an image obtaining unit for obtaining an image of the fine pattern as an inspection image. The image obtaining unit produces an image signal representing the inspection image. The image signal is stored into an image memory as a stored image signal. The pattern inspection device further comprises an auxiliary memory memorizing a reference image signal as a stored reference image signal. The reference image signal represents a reference image of the fine pattern that has no defect. The stored image signal is compared with the stored reference image signal by the use of a pattern recognition method which is known in the art.
In the fine pattern inspection device mentioned above, it is required to provide with the auxiliary memory having a large capacity. This means that the fine pattern inspection device becomes large in size. Furthermore, it is required to match the inspection image with the reference image for pattern recognition. It is therefore required to have a matching time duration for the pattern recognition. This means that an inspection time duration becomes long.